12 Tools to check the duplicate content

http://www.copyscape.com/
http://www.virante.org/seo-tools/duplicate-content
http://www.webconfs.com/similar-page-checker.php
http://www.dupefreepro.com/
http://www.plagium.com/
http://www.duplichecker.com/
http://www.articlechecker.com/
http://plagiarisma.net/
http://www.plagiarismchecker.com/
http://dupecop.com/
http://www.copygator.com
http://www.copyrightspot.com